Question

Which statement is NOT correct? (According to Valence bond theory)

• A. A sigma( $\sigma$ ) bond is weaker than a $\pi -$ bond
• B. A sigma bond is stronger than a $\pi -$ bond
• C. A double bond is stronger than a single bond
• D. A double bond is shorter than a single bond

Answer 1

Answer: (A)

A $\sigma$ - bond is stronger than a $\pi$ - bond.
Sigma $(\sigma )$ bonds are formed by head on overlap of unhybridised
$s-s,p-p$ or $s-p$ orbitals and hybridized orbitals
$(\mathrm{sp},{\mathrm{sp}}^2,{\mathrm{sp}}^3,{\mathrm{sp}}^3\mathrm{d}$ and ${\mathrm{sp}}^3{\mathrm{d}}^2)$ Hence, $\sigma$ bond are strong bonds.
Where as $Pi(\pi )$ - bonds are formed by side ways overlap of unhybridised p and d orbitals. Hence $\pi$ bonds are weak bonds.